Electrical switching device for high switching voltages

Abstract

An electrical switching device for switching high voltages in a network having a defined rated voltage. The device includes a series connection of at least first and second current interrupters having control elements across which a load voltage is distributed. Each interrupter operates according to different quenching principles and exhibits different dielectric behavior immediately after a zero passage of load current to be interrupted. The first interrupter comprises a first switch which has an operating voltage that is low relative to a mains voltage of the network and includes means for interrupting, at relatively low switching voltages without participation of the second interrupter, currents having inductive components. The second interrupter comprises a second switch having switching contacts and delay means for opening such switching contacts with a time delay of several milliseconds after the first interrupter is opened for interrupting load currents that are small relative to currents interrupted by the first interrupter. The series connection of the interrupters interrupts capacitive currents also under grounding conditions with comparatively large recovery voltages and without restriking, with a distribution of voltage across the interrupters, when both are open, being controlled solely by their own ground capacitances.

What is claimed is: 
     
       1. In an electrical switching device for switching high voltages in a network having a defined rated voltage, the device including a series connection of at least first and second current interrupters having control elements across which a load voltage is distributed, each interrupter operating according to different quenching principles and exhibiting different dielectric behavior immediately after a zero passage of load current to be interrupted, the first interrupter exhibiting a steep rate of rise in its dielectric strength with a maximum dielectric strength value which is a fraction of the defined rated voltage, and the second interrupter having a relatively flat rate of rise in dielectric strength compared to the first interrupter with a maximum dielectric strength value which lies above the maximum dielectric strength value of the first interrupter; the improvement wherein: said first interrupter comprises a first switch which has an operating voltage that is low relative to a mains voltage of the network and which includes means for interrupting, at relatively low switching voltages without participation of said second interrupter, currents having inductive components; and   said second interrupter comprises a second switch having switching contacts and delay means for opening said switching contacts with a time delay of several milliseconds after said first interrupter is opened, for interrupting load currents that are small relative to currents interrupted by said first interrupter;   wherein said series connection of said interrupters interrupts capacitive currents also under grounding conditions with comparatively large recovery voltages and without restriking, with a distribution of voltage across said interrupters when both are open being controlled solely by their own and ground capacitances.   
     
     
       2. Electrical switching device as defined in claim 1, wherein the time delay is equal to an average of the duration of arcs across said first switch for load currents having inductive components. 
     
     
       3. Electrical switching device as defined in claim 1, wherein said first switch is a vacuum load switch and said second switch is a low power load switch operating with a gaseous quenching agent. 
     
     
       4. Electrical switching device as defined in claim 3, wherein said gaseous quenching agent is SF6. 
     
     
       5. Electrical switching device as defined in claim 1, wherein said second interrupter does not have a closed interrupting unit and has an extinguising medium which simultaneously increases outer insulation of said first interrupter. 
     
     
       6. Electrical switching device as defined in claim 5, wherein said second interrupter simultaneously constitutes a disconnecting switch. 
     
     
       7. Electrical switching device as defined in claim 1, and further comprising separate drives for each of said switches, said separate drives being coupled mechanically with one another. 
     
     
       8. Electrical switching device as defined in claim 1, wherein said second switch comprises a pivot arm and said first switch is integrated in said pivot arm and is actuated in dependence on the position of said pivot arm. 
     
     
       9. Electrical switching arrangement comprising a plurality of said switching devices as defined in claim 7, and a common gas tight encapsulation encapsulating said plurality of switching devices. 
     
     
       10. Electrical switching arrangement as defined in claim 9, wherein three-pole units of said switching devices are encapsulated by said encapsulation. 
     
     
       11. Electrical switching arrangement as defined in claim 9, and further including a moisture absorber disposed within said encapsulation. 
     
     
       12. Electrical switching device as defined in claim 1, wherein said second switch includes an insulating fluid as its quenching agent. 
     
     
       13. Electrical switching device as defined in claim 12, wherein said insulating fluid comprises a switch oil. 
     
     
       14. Electrical switching device as defined in claim 1, wherein, said second switch has an operational position, an open position and a position for grounding the network, and further including means for effecting said grounding by successive closings of said first and second switches. 
     
     
       15. Electrical switching device as defined in claim 1, wherein said second interrupter does not have a separate interrupting unit and has an extinguishing medium which simultaneously increases outer insulation of said first interrupter. 
     
     
       16. Electrical switching device as defined in claim 1, wherein said second interrupter does not have at least one of a closed interrupting unit, a separate interrupting unit, and an arc chute and has an extinguishing medium which simultaneously increases outer insulation of said first interrupter. 
     
     
       17. Electrical switching device as defined in claim 1, and further comprising separate drives for each of said switches, said separate drives being coupled electrically with one another. 
     
     
       18. Electrical switching arrangement comprising a plurality of said switching devices as defined in claim 7, and a common liquid tight encapsulation encapsulating said plurality of switching devices.